3D tomographic reconstructions require projection images as input. A projection image assumes that an object of interest is translucent to a source of exposure such as a light source transmitted through the object of interest. The projection image, then, comprises an integration of the absorption by the object along a ray from the source to the plane of projection. Light in the visible spectrum is used as a source of exposure in optical projection tomography.
In the case of producing projections from biological cells, the cells are typically stained with hematoxylin, an absorptive stain that attaches to proteins found in cell chromosomes. Cell nuclei are approximately 15 microns in diameter, and in order to promote reconstructions of sub-cellular features it is necessary to maintain sub-micron resolution. For sub-micron resolution, the wavelength of the illuminating source is in the same spatial range as the biological objects of interest. This can result in undesirable refraction effects. As a result a standard projection image cannot be formed. To avoid these undesirable effects, as noted above, the camera aperture is kept open while the plane of focus is swept through the cell. This approach to imaging results in equal sampling of the entire cellular volume, resulting in a pseudo-projection image. A good example of an optical tomography system has been published as United States Patent Application Publication 2004-0076319, on Apr. 22, 2004, corresponding to U.S. Pat. No. 7,738,945 issued Jun. 15, 2010, to Fauver, et al. and entitled “Method and Apparatus for Pseudo-Projection Formation for Optical Tomography.” U.S. Pat. No. 7,738,945 is incorporated herein by reference.
An optical tomography system may advantageously employ scores for classifying objects of interest, for example, to detect lung cancer in its pre-invasive and treatable stage. In order to do so with accuracy and reliability, the classification scores must be based on good quality 3D reconstruction images of the objects being classified. One example of an optical tomography system is being built by VisionGate, Inc. of Gig Harbor Wash., assignee of this application, is under the trademark “Cell-CT™.” In one aspect, the Cell-CT™ optical tomography system employs scores, designed to provide an indication of lung cancer in its pre-invasive and treatable stage.
While it is generally understood that poor quality 3D reconstructions may adversely affect classification results in optical tomography systems, an automated system for detecting such poor quality 3D reconstructions has been lacking until now. The system and method disclosed herein provides, for the first time, a solution for detection of poor quality 3D reconstructions useful for an optical tomography system, for example.